1. Field of the Invention
The present invention relates to an ophthalmic photography apparatus, and more particularly an ophthalmic photography apparatus that is capable of capturing a monocular image of an ocular fundus and stereographically viewed images thereof.
2. Description of the Prior Art
Fundus cameras are conventionally known wherein a photographic stop having two left and right apertures (two-aperture stop) is disposed in a position conjugate with an anterior ocular segment (conjugate with a pupil) of an eye under examination. Reflected light from an ocular fundus passing through the apertures is captured as stereographically viewed left and right images by a film or an imaging element.
Fundus cameras are also known wherein a stereographic photography function is incorporated into a typical fundus camera having an illumination stop and a photographic stop, which are interlinked so as to be able of capturing monocular images and stereographically viewed images (Japanese Laid-open Patent Publication No. 2007-185324).
Fundus cameras are also known in which the wavelength of illuminating light is selected to correct a misalignment of focusing position because the ocular fundus is brought out of focus during specialized photography such as fluorescence photography (Japanese Laid-open Patent Publication No. 2000-268733).
A fundus camera capable of monocular photography and stereographic photography as described in the abovementioned Japanese Laid-open Patent Publication No. 2007-185324 can capture a clear fundus image when the ocular fundus is brought into focus using the photographic stop for monocular photography. However, when the two-aperture stop is selected in this state for stereographic photography, drawbacks are manifested in that defocus occurs and a clear fundus image cannot be obtained. The problems arise from a change in the optical length due to the fact that the position of the apertures used for stereographic photography deviate from the photographic optical axis.
It is therefore an object of the present invention to provide an ophthalmic photography apparatus capable of readily correcting defocus generated by deviation of the apertures of a photographic stop from the photographic optical axis even when switching between monocular photography and stereographic photography.